Hitherto, an apparatus that detects a sleepy state of a driver in a vehicle has been proposed as this type of sleepiness assessment apparatus (for example, see PTL 1). In this apparatus, by utilizing the fact that activities of the sympathetic nervous system increase in a case where a person is in a state in which the person struggles against sleepiness, a time series of a cardiac cycle is acquired from a cardiac signal detected by a heartbeat sensor. Additionally, the amplitude spectral power of a low-frequency component of heart rate fluctuation is acquired from the time series of the cardiac cycle. When the amplitude spectral power of the low-frequency component of the heart rate fluctuation is larger than a predetermined value, it is determined that the degree of arousal is reduced. Note that, when it is determined that the degree of arousal is reduced, a stimulus, for example, a sound such as a buzzer, light such as meter illumination, or vibration, is applied in order to increase the degree of arousal of the driver.